Many known room occupancy sensors use Passive Infrared (PIR) motion sensors (sometimes commonly referred to as occupancy sensors) located on the ceiling and/or wall and/or near a doorway in a room to determine whether a person is present in the room and control the lighting and/or environmental conditions in the room accordingly. For example, known occupancy sensors sense a person entering a previously unoccupied room when the entering person traverses one or more PIR beams from a PIR motion detector positioned to monitor a doorway and based on the sensing, actuates or enables the room's lighting in the occupied state to illuminate the room. Subsequent motion in the room by the occupying person provides for maintaining the occupied state (and the illuminated lighting) by re-triggering the PIR motion detector positioned at the entrance and/or positioned on the ceiling and/or wall.
When a person is seated at a desk, however, the person's motion may be so slight (micro-motion) that it is insufficient to properly trigger a PIR motion detector (the backbone of conventional room occupancy sensors) to maintain the occupied state and the supply of current to the room or monitored zone. PIR motion detectors only respond when the target crosses at least one passive beam, formed by a multi-faceted lens that is operates to direct the beam to a PIR motion detector as part of the conventional occupancy sensor and a person's smaller motions at times do not cross the beam zone boundaries so detection is not determined. So where further “presence” detection is required to maintain an occupied status, the occupancy sensor may change the status to “unoccupied” by failure to detect small micro-motions and consequently inadvertently interrupt the source of electrical power. If the room was illuminated prior to the change of status from occupied to unoccupied, the lights become extinguished as the conventional sensor stops the supply of electrical current with said change of state.
At that point, the person seated at the desk experiences the lights being switched from an “on” state to an “off” state and must wave their arms or stand up and walk to cross a beam in order to re-trigger the motion sensor to change back to an occupied state and thereby again actuate the room's lighting.